研究目的
To study the influence of parameters on porosity defect, weld formation, and property of the joints in laser-MIG hybrid butt welding of 5 mm-thick 304 stainless steel.
研究成果
Laser-MIG hybrid welding of 304 stainless steel has porosity sensitivity. Increasing laser power or decreasing welding speed would result in reducing the porosity of the weld. Weld formation reflects the stability of the welding process. The tensile strengths are 628 and 631 MPa, respectively, when laser powers are 4.3 and 5.0 kW, which reaches at least 98.1% of the base metal’s strength (640 MPa). Although the tensile strength of the welded joint is close to that of the base metal, there is still some elongation loss in the welded joints, which can only reach up to 78.5% of the base metal at most when laser power is 5.0 kW.
研究不足
The study focuses on the influence of welding speed and laser power on porosity and joint properties, but other parameters such as arc energy and gas shielding are not extensively explored. The research is limited to 5 mm-thick 304 stainless steel, and the findings may not be directly applicable to other materials or thicknesses.
1：Experimental Design and Method Selection:
Laser-MIG hybrid butt welding was carried out on 5 mm-thick 304 stainless steel to study the influence of parameters on porosity defect, weld formation, and property of the joints.
2：Sample Selection and Data Sources:
304 austenitic stainless steel of 5 mm was used as the base metal (BM). The specimens were machined with dimensions of 200 × 80 × 5 mm3 without groove. ER308 austenitic stainless steel with a diameter of
3：2 mm was used as the filler wire. List of Experimental Equipment and Materials:
Laser-MIG hybrid welding system is composed of a Trumpf TruDisk 10002 continuous-wave disk laser apparatus, a Fronius TPS 5000 welding machine, and a laser-MIG hybrid welding torch.
4：Experimental Procedures and Operational Workflow:
Laser-MIG hybrid butt welding without gap was carried out on 304 stainless steel. The specimens were polished and cleaned by acid and alkaline before welding.
5：Data Analysis Methods:
Welded specimens were sectioned perpendicular to the weld direction for microstructure analysis. The specimens were polished and then etched with solution whose composition is FeCl3–HCl–H2O (5 g: 30 ml: 100 ml). The macrostructure and microstructure of the weldments were examined using optical microscopy (OM, MM-400D). The phase characterization was performed by x-ray diffraction (XRD, D/max-RB 12 kW). The microscopic characteristics of pore defects were analyzed by scanning electron microscopy (SEM, Quanta 250), and the radiographic test was measured by an x-ray flaw detector.
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